This might be more a Zigbee than an Openhab question …
On openHAB 2.5.0~M6-1 I’m running this (simple) Zigbee network:
Nortek Zigbee/Z-Wave USB Stick ( Ember EM35x Coordinator) -> Device Type COORDINATOR
MuellerLicht ZigBee Light Bulb -> Device Type ROUTER
Eurotronic SPZB0001 Thermostat -> Device Type END_DEVICE
The light bulb is not always online (classic power switch), but every time is becomes online the thermostat is connecting to the bulb (as it is a router). When the bulb is switched off, the thermostat is loosing the network connection and can’t be reached anymore until the bulb is switched on again.
Is there a way to force the thermostat to connect to the Ember Coordinator only? Or to configure the bulb not to accept the thermostat as a Zigbee neighbour?
No - not really. When the binding opens up the network for joining, it allows devices to join to any router (the coordinator is just a router after all). The device will then attempt to join the device with the best link quality.
In theory it’s possible to open joining just with a specific router, but the binding doesn’t support this (I doubt many systems do this).
You could try to move the coordinator closer to the device when it joins, although in theory the end device ought to leave the network and rejoin if it finds that its parent is not available, so it should (!!) sort itself out if the end device has been programmed to support this.
Remember also that the coordinator (as with any router) can only handle a small number of neighbours, so unless you have a very small network this will become a limitation if you try to connect everything to the coordinator.
Thanks for your comprehensive reply! That made things clearer.
I made some tests and it looks as if the thermostat (end device) changes to the bulb (router) as soon as it is switched on and never wants to connect back to the Nortek/Ember USB stick (coordinator) once the bulb is switched off again. Now I’m thinking about my options … for now it might be the quickest solution to change the Zigbee thermostat to a Z-Wave device, which is also supported by the Nortek USB stick.
